What is being displayed in that video I'm pretty sure is not cavitation. It is just aerated water from turbulence. If you feed aerated water into a pump it will never pump efficiently.
There's another video where the impellor was swapped out to his one with zero other changes and all those bubbles were virtually gone, so read into that what you will. I really have no idea, I just found the video and thought you guys might like to see it.What is being displayed in that video I'm pretty sure is not cavitation. It is just aerated water from turbulence. If you feed aerated water into a pump it will never pump efficiently.
I was impressed by the sheer volume of water that was being moved about though.
Pressure loss is directly proportional to hose length. period,You need to look at the radiator, bottom hose and thermostat as one. The radiator feeds the bottom hose which feeds the lower thermostat housing. This goes right past the bypass, so distance or length is not a consideration. The bypass hole is approximately 18mm while the radiator supply is over 40mm. Then there is the head pressure of the radiator being higher than the bypass, which if you remove the upper thermostat housing and thermostat, the water will gizer out of bypass hole until the level of the radiator matches the bypass level.
Then with the bypass, is it anything but a nice transition of passage for the water from out of the head around the thermostat around corner to a hole with poor radius and transition.
Using pressure and vacuum gauges on the system with standard bypass and plumbing, a drop in pressure is noted on thermostat opening. Less resistant =Less pressure.
Pressure loss is directly proportional to hose length. period,
there are formulas out there to work this stuff out.
Head pressure of a radiator has nothing to do with a bypass,
The bypass is on the suction side of the pump,
there will be no head pressure from the radiator affecting it under running conditions,
Unless you think any head pressure in the radiator
can overcome the flow from the thermostat to the radiator?
Where was this measured a drop in pressure noted on thermostat opening?
because the laws of physics are pretty clear that a drop in pressure,
with a lengthed path for the water,
would indicate that resistance has increased.
Showing that that radiator is indeed a path of greater resistance over the bypass.
Because water is already flowing through the bypass at capacity,But can you explain to me, why is it when the thermostat opens, albeit even as little as 1mm, it sends water through this gap through the radiator.
Wouldn't the water take the easier path through the open hole of the bypass??
Because water is already flowing through the bypass at capacity,
because it is indeed the path of least resistance.
The video Kiwi_dingo put up shows the volume the pump is capable of.
Once a route is saturated/at capacity the next easiest path
or in this case the only other path will take the overflow/excess.
You can only get so much flow through any hose until it reaches capacity
and then resistance then increases.
Water flowing through the radiator when the bypass opens as little as 1mm
doesn't prove nor show that the radiator is the path of least resisitance.
Perhaps i should have been clearer with my earlier statements/hypothesis
but i thought you had a basic grasp of fluid dynamics.
I have already proved to myself and stated so earlier in this thread
that cavition or aeration if you prefer increases when the bypass fully closes
and all coolant is sent throught the radiator.
Leading me to believe, along with basic physics,
that the longer path through the radiator will increase fluid drag/resistance
and the suction of the pump aerates the coolant even more
and then it's all downhill for the cooling systems ability to hold temps under control.
However keep the bypass open which in turn reduces cavitation/aeration on the suction side of the pump and it's all happy sailing.
Again, this is just what i've proven with my setup.
Another hint is that early on is this thread people where reporting greater temperature control
with hotter thermostats.
When you consider the wax pellet thermostat is linear in operation with regards to temperature,
it can only mean that the later or hotter a thermostat opens will also mean a hotter/later tempature that the thermostat is fully open, which also means a later fully closed bypass.
Again since an open bypass allows the pump to pump more efficiently with less aeration/cavition,
higher stable temperatures are reached before the cooling system can't hold on and runs away.
You didn't discuss anything about what i posted,There's alot here to discuss.
The rest is irrelevant if you can't sort the pump.
You didn't discuss anything about what i posted,
just rambled on about stuff other people have done for you.
The rest is not irrelevant if it's causing aeration
or at its extreme, cavitation at the pump.
How did you test the maximum flow of the bypass?
How would you test this? and more to the point why do you need to test this? It's a hole mere inches from the suction side of the pump, if the bypass is open there will be the maximum flow allowable due to the size of the aperature and the fact it's the path of least resistance till it reaches capacity of course, the bypass isn't capable of flowing all the pump can move.
Was the bypass like kiwi dingo' s video?
Half full of bubbles.
Sorry don't have x-ray vision,
But since getting my cooling system to the point, where the bypass is always open at least a little bit
and this has prevented the cooling system running away uncontrollably when pushed hard,
I'm going to say no.
Just removing the bubbles would increase water volume.
How have you checked for cavitation??
No pitting on the front timing cover,
it's alloy and the closest to the source and most susceptible to pitting.
How have you measures pump efficiency?
It holds temps stable towing 3 ton, i'd say it works ok.
P.S. This just shows you only read what you want to read,
i've stated this stuff before earlier in this thread,
but it doesn't conform to your viewpoint so you discard it.
Yes, the bypass cannot efficiently move all the coolant,
when the bypass is fully open (thermostat fully closed) pressure in the block will be high.
Pressure is a measurement of resistance to flow, same as boost.
A simple pressure test in the block/head when the thermostat is shut (bypass open)
and another when the thermostat starts to open will confirm this.
Pressure will be high will thermostat is shut (bypass open) and the pressure will drop when the thermostat opens.
Because for about the umpteeth time,
the bypass being open minimizes pump aeration. (even if it's just open 2-3mm or so)
You don't need or want the thermostat to fully open or fully shut the bypass to control temps.
I've found it's the closing of the bypass when the thermostat is fully open that causes the aeration/cavitation in the pump
due to the longer more restrictive path through the radiator with a standard oem style water pump.
Remember, the thermostat does 2 things at once,
it allows the pump to draw water from the radiator when the thermostat starts to open
and at the same time it also controls the bypass flow.
you seem to think the bypass must be either fully closed or open?